The purpose of this study is to determine whether the time to progression in patients with metastatic renal cell carcinoma is doubled from 4 months (historical control data) to 8 months following the initiation of treatment with C225 when administered by weekly intravenous infusions at a loading dose of 400 mg/m2 followed by maintenance doses of 250 mg/m2. This is a multicenter, open label, non-randomized Phase II study with a single dose level. Patients will receive a "test dose" prior to the initial loading dose only. The patient will receive a 10 mL (20 mg) infusion over 10 minutes and will be observed for a period fo 30 minutes post administration for signs of anaphylaxis. Patients may receive the remainder of their infusion following completion of the observation period. All patients will receive C225 at a loading dose of 400 mg/m2 followed by maintenance doses of 250 mg/m2 IV weekly for seven weeks. In the absence of progressive disease or intolerable toxicity, patients may continue to receive further courses of weekly treatment with C225 for a maximum treatment course of 6 months (i.e., 3 courses). Subsequent courses of therapy will be administered at the maintenance dose level of 250 mg/m2 for 8 weekly doses. Folowing the initial 6 months of treatment, patients who have not progressed may continue to receive treatment for an additional 6 months.